In particular for the treatment of service water, it is counted as belonging to the state of the art to let this water flow preferably through rotating stacks of filter elements, in particular filter plates, which is typically arranged in a closed container, with which the medium to be filtered within the container is fed on the outer side of the filter elements, and the filtrate is drawn off as a rule through the filter elements centrally through a shaft or several channels running through the filter element stack. Thereby, it is necessary to clean the filter elements at regular intervals, in order to prevent these from permanently clogging. This can be effected by mechanical wipers/scrapers and/or by way of backflushing.
Independently of how the cleaning of the filter elements is accomplished, these are to be replaced after a certain service life, and thus it is the case of wearing parts. Thus, a basic problem is to be able to manufacture these filter elements as inexpensively as possible. Thereby, the filter elements which are known from EP 1 807 184 B1 and consist completely of plastic are particularly economical, with which a free space for the removal of the filtrate is formed between two filter membranes by way of a fabric. These filter elements although being inexpensive in manufacture, in practice are only useable to a restricted extent, since inherent to its design, a backflushing can only be effected with a comparatively low pressure, and moreover a rotation of the filter element stack constructed of such filter elements is a problem due to the quite low intrinsic stability of the filter elements.
The filter disks known for example from EP 2 002 874 B1 are more favorable as far as this is concerned, with which filter disks the membrane consists of a ceramic material, and two membranes are connected to one another via an intermediately lying carrier body which at the same times holds the ceramic disks at a distance to one another and provides free space for the through-flow. Such filter elements although having a high serviceable life, since they can be backflushed at high pressures, however, are quite extensive in manufacture.